1. Field of the Invention
The invention relates to an antiwear coating especially for components which are subject to erosion under mechanical stress, in particular for gas turbine components, which consists of at least two different individual layers which have been applied in a multiply alternating manner with one another to a surface to be coated of a component.
2. Discussion of Background Information
Gas turbine components are provided with an antiwear layer for protection against wear, especially erosion and corrosion. This antiwear layer consists of a plurality of individual layers composed of different materials, as is known from the document DE 10 2004 001 392.6. Here, a metallic layer is firstly applied to a component in order to make good bonding of the antiwear layer to the metallic substrate material possible. This is followed by a metal alloy and a gradated metal-ceramic material. This multilayer system is concluded by a ceramic layer. This multilayer system can also be deposited a plurality of times on top of the first multilayer system, always commencing with a metallic layer to achieve better bonding to the metallic substrate material and ending with a ceramic layer on the surface. In addition, a bonding layer can be inserted between the first multilayer system and the component.
In general, such multilayer systems based on this principle are made up of hard (main) and soft (intermediate) layers. The main layers have a high erosion resistance and the intermediate layers have a high ductility. As a result, cracks which form in the case of overloading in the multilayer structure are stopped in the ductile intermediate layers by blunting of the crack tips.
To prevent erosion, structuring the hard ceramic layers of a multilayer system is known from the document DE 10 2006 001 864.8. Such ceramic layers are segmented in the vertical direction in a columnar manner in order to prevent detachment of relatively large regions of the layer during particle erosion attack. Here, the columnar segmentation is in the form of columns or stems or fibers. The interfaces between the columns of the layers segmented in a columnar fashion prevent the growth of microcracks in the direction parallel to the surface which can be caused during erosive stress. However, it is a disadvantage that cracks in the vertical direction can be propagated unhindered along the interfaces. When a component is stressed, these interfaces between columns act as micronotches or initial microcracks. In the case of severe overstressing, the ductile intermediate layers can no longer stop the arriving microcracks and the latter grow into the substrate material. The microcrack formed under tensile stress can propagate far into the substrate material and lead to premature failure of the component. This has the substantial disadvantage that the life of a component is considerably reduced.
It is therefore an object of the invention to provide an antiwear layer which firstly increases the life of a component and secondly prevents microcrack formation.